Cancellation not Processed

We had 2 tablet contracts with Telkom. Contracts finished December 2015. One contract was converted to a wifi deal and the other to data only. We are being billed for wifi which is correct and for a tablet not at the original contract price but full price...This is not correct as we were to be charged for data only. We are currently paying more than the original contract charges. We went to the store and cancelled the second tablet on 30th January 2016. Case number ***2 refers. One month cancellation period ended month end February. We have now received data on 1st March which should not have been as the contract is cancelled. We are not liable for payment as contract for the tablet is cancelled. We also require any refund to be credited to our Telkom account. We require an urgent response. <br>